Jing-Fang n-butanol extract and its isolated JFNE-C inhibit ferroptosis and inflammation in LPS induced RAW264.7 macrophages via STAT3/p53/SLC7A11 signaling pathway

Traditional Chinese medicine has accumulated valuable experience in the treatment of inflammatory diseases caused by Ferroptosis. Jing Jie and Fang Feng are two warm acrid exterior-resolving medicinal herbs that play an important role in the prevention and treatment of inflammatory diseases. The pairing of the two forms a drug pair (Jing-Fang) that shows significant advantages in fighting oxidative stress and inflammation. Whereas, the underlying mechanism needs to be further improved.In this study, the anti-inflammatory effect of Jing-Fang n-butanol extract (JFNE) and its isolate C (JFNE-C) on LPS-induced RAW264.7 cells and the regulation effect on ferroptosis were investigated, and also the mechanism of STAT3/p53/SLC7A11 signal pathway-related to ferroptosis.Jing-Fang n-butanol extract (JFNE) and its active isolate (JFNE-C) were extracted and isolated. LPS-induced inflammation model in RAW264.7 cells was established to assess the anti-inflammatory effect and ferroptosis mechanism of JFNE and JFNE-C. The levels of interleukin 6 (IL-6), interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) were measured. The activity levels of antioxidant substances such as glutathione (GSH), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) were measured. Flow cytometry, immunofluorescence and transmission electron microscopy were used to assess ROS level, ferrous iron content and mitochondrial morphological changes. Through administration of Ferrostatin-1 (Fer-1), an ferroptosis inhibitor, to verify the role of JFNE and JFNE-C in regulating ferroptosis in resistance to the inflammatory response. Western blotting was used to determine whether the JFNE and JFNE-C exerted effectiveness by modulating the STAT3/p53/SLC7A11 signaling pathway. In addition, the important role of STAT3/p53/SLC7A11 signaling pathway in drug regulation of ferroptosis and inflammatory response was further validated by administration of S3I-201 (STAT3 inhibitor). Finally, high performance liquid chromatography-mass spectrometry (HPLC-MS) was used to determine the major active components of JFNE and JFNE-C.The results showed that treated with JFNE-C significantly reduced the contents of interleukin 6 (IL-6), interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) in the supernatant of LPS-induced RAW264.7 cells. The pretreatment with JFNE and JFNE-C significantly decreased intracellular oxidative stress levels, including reductions of ROS and MDA levels, and increases of GSH-Px, SOD and GSH levels. In addition, JFNE and JFNE-C obviously reduced intracellular ferrous iron level, and JFNE-C was effective in alleviating mitochondrial damage which includes mitochondrial shrinkage, increase of mitochondrial membrane density and reduction and absence of cristae. Further results indicated that JFNE-C showed a reduction of p53 and p-p53 protein levels in LPS-induced RAW264.7 cells, while significantly increasing the protein expression levels of STAT3, p-STAT3, SLC7A11 and GPX4. Besides, JFNE-C contains key active substances such as 5-O-Methylvisammioside, Hesperidin and Luteolin. Remarkably, this is different from JFNE, which is rich in nutrients such as sucrose, choline and various amino acids.These results suggest that JFNE and JFNE-C may exert anti-inflammatory effect through activating the STAT3/p53/SLC7A11 signaling pathway to inhibit ferroptosis.